Explosive-actuated tools



Oct. 21, 1969 R. D. WACKROW 3,473,718

EXPLOSIVE-ACTUATED TOOLS Filed Nov. 21, 1966 2 Sheets-Sheet 1 IN VE/V7'0R ROGER DA V/D WAC/(ROW ATTORNEYS Oct. 21, 1969 R. D. WACKROW3,473,718

EXPLOSIVE-ACTUATED TOOLS Filed Nov. 21, 1966 2 Sheets-Sheet 2 IN VE/V70R ROGER DA V/D WAC/(ROW ATTOR/VEKS United States Patent US. Cl. 227 4Claims ABSTRACT OF THE DISCLOSURE An explosive-actuated tool for drivinganchoring members into hard materials comprising a body having a pistonmovably mounted therein and a chamber formed at one end of the body, thehead of the piston being movable into the chamber which has a stop meansat the end thereof to limit piston movement. A locking cap is releasablysecured on the end of the body and axially movable relative thereto. Thecap supports a cartridge adjacent the body chamber and includesresilient means which normally restrains axial movement of the caprelative to the body and thereby holds the cartridge away from thechamber stop means and the piston head abutting thereagainst. Thecartridge will only be fired when the piston abuts the stop means andwhen an end force is applied against the cap to overcome the restrainingforce of the resilient means.

This invention relates to explosive actuated tools for driving nails,studs, pins, bolts and other members, hereinafter referred to asanchoring members, into hard materials.

Such tools normally comprise a cartridge supporting member and acartridge striking member which are relatively moveable into and out ofcontact so that sudden contact between the two members caused by a blowdelivered to one of the members causes a cartridge located in thecartridge supporting member to be fired. The expanding gases of thefired cartridge then normally drive a piston along a tube, this actiondriving an anchoring member out of the tube and into a wall or the like.The cartridge striking member is normally part of the piston, usually inthe form of a firing pin secured to one face of the piston or in theform of a suitably shaped piston face. The cartridge supporting membermay be a further piston or may form part of an end cap releasablysecured to the body of the tool.

It has been found desirable to provide explosiveactuated tools withsafety devices to prevent accidental or inadvertent firing of the toolduring normal working and handling operations, and it is an object ofthe present invention to provide means for preventing the inad vertentfiring of an explosiveactuated tool on occas sions such for example aswhen the tool is knocked, dropped from a reasonable working height orwhen an attempt is made to load an excessively large anchoring memberinto the tool.

According to the present invention an explosiveactuated tool for drivinganchoring members into hard materials has a body in which are moveablymounted two members, one member being adapted to support a cartridge andthe other member to strike the cartridge, there being provided in thebody stop means for preventing the first member from moving into contactwith the second member, and resilient means for preventing the secondmember from moving into contact with the first member until suchresilient means is compressed, deformed or otherwise overcome.

Preferably the member adapted to support the cartridge comprises an endcap which is releasably secured to the end of the body and is normallyheld a short distance clear of the end of the body by a spring mountedbetween the end cap and the end of the body.

A plunger may also be used in conjunction with the spring, and theplunger may additionally serve to pro- ;ide resistance to rotation ofthe end cap relative to the ody.

The member which is adapted to strike the cartridge preferably comprisesthe head of a piston which is adapted to drive an anchoring member intoa wall or the like when the cartridge is fired.

The piston is preferably prevented from moving into contact with the endcap by means of a suitable stop formed on the end of the body.

The tool can only be fired when the piston and the end cap contact eachother, and this may only occur when the piston is held firmly againstthe stop at the end of the body and the end cap is struck hard enough toovercome the spring. An impact on the piston alone will not fire thetool (provided the end cap spring is not depressed) as the piston willmerely hit the stop at the end of the body, and similarly an impact onthe end cap alone hard enough to overcome the spring will not fire thetool if the piston is not held firmly against its stop at the sameinstant. The tool is thus provided with an effective safely device.

An embodiment of the invention will now be described by way of examplewith reference to the accompanying drawings in which:

FIG. 1 is an external view of the complete tool,

FIG. 2 is a sectional view of the tool, and

FIG. 3 is a sectional view of the tool locking cap on an enlarged scale.

The explosive-actuated tool comprises a body part 1 having a forwardlyextending portion in the form of a barrel 2 supported for movementco-axial with the body part by means of a screwed nut 3 engaging anenlarged end portion of the barrel also serving as an abutment for oneend of a spring 4a located within the body part 1 and engaging a washer4.

A piston 5 in the form of an elongated rod or shank enters a bore 6 inthe barrel 2 and engages with the head of the stud or nail 10 to befired, the nail being inserted in a guide member constituting a cap 9secured to the end of the barrel 2, a recess in the cap receiving aguide washer normally mounted on the nail. A short head portion 7 of thepiston 5 is adapted to enter a chamber in the body on a force beingapplied to the point of the nail 10, the rearward axial movement ofpiston head 7 in chamber 7a being limited by engagement with the stopshoulder 7b formed at the end of chamber 7a. When the rim of a cartridgelocated in a locking cap 11 is struck on impact with the piston head 7,the cartridge is fired and gases are passed into the chamber 7a behindthe piston.

The body part 1 of the tool is surrounded by a hand grip 8, andterminates in the aforesaid locking cap 11 which is releasably securedto the body by means of alternate shoulders 12 and recesses 12:: on boththe body and the cap, a clearance between the shoulders and recessesproviding for an axial movement of the cap relative to the body when thecap is struck by a hammer to cause the piston head 7 to detonate acartridge. As seen in FIG. 3, complete rotation of the cap relative tothe body for locking and unlocking is prevented by means of a stop pinin the form of a split sleeve 13 mounted in a bore formed in the cap,means for normally holding the cap clear of the end of the bodycomprising a plunger 15 loaded by a spring 16 both mounted in a furtherbore 14 in the locking cap and retained therein by a grub screw 17. Byreason of the contact of the nose of the spring-loaded plunger 15 withthe end of the body in conjunction with the resistance to rotationprovided by the stop pin, an impact on the locking cap will not fire thetool as aforesaid unless it has been adequate to overcome the plungerspring by a deliberate hammer [blow on the cap sufiicient to bring thecartridge into contact with the piston after the tool has been broughtto the firing position by pressing it against a wall or other objectinto which the nail or stud is to be driven.

In operation, the locking cap 11 is released from the body part 1 of thetool by a part rotation to align the alternate shoulders 12 and recesses12a, a cartridge is inserted, and the cap reconnected to the body by apart rotation to engage the aforesaid shoulders and recesses, suchrotation of the cap 11 into the locking and unlocking positions beingcontrolled by the pin 13.

A nail 10 is then inserted into the guide member 9 on the end of thebarrel 2, and the tool is pressed against the surface into which thenail is to be driven until the member 9 contacts the surface and thehead of the nail contacts the end of the piston 5. This movementeffected through the hand grip 8 causes the body part 1 to move relativeto the barrel 2 against the spring 18, whereby the chamber 7a is movedover the head portion 7 of the piston, movement of the body part 1 beingstopped when the piston head 7 contacts with the rear face 7b of thechamber 7a. The tool is now fired by striking the cap 11 with a hammer,which causes the cap to move axially for a short distance against thespring 16 of the plunger 15 until the cartridge is fired on contact withthe piston head 7.

What I claim is:

1. An explosive-actuated tool for driving anchoring members into hardmaterials comprising a body, piston means axially movably mounted insaid body, a chamber formed in one end of said body adapted to beentered by said piston means, said chamber means having stop meanslimiting the movement therein by said piston means, a locking capreleasably secured to said one end of said body and axially movablerelative thereto when mounted thereon, said cap having means forsupporting a cartridge adjacent said chamber, resilient meansrestraining axial movement of said locking cap for normally holding saidcartridge support means axially spaced from said stop means, wherebysaid cartridge will not be fired by striking said piston means untilsaid piston means engages said stop means and said end cap is displacedto overcome the restraining force of said resilient means.

2. An explosive-actuated tool according to claim 1, said cap ibeingreleasably secured to said body by interengaging shoulders and recesseshaving axial clearance therebetween to permit axial movement of said caprelative to said body.

3. An explosive-actuated tool according to claim 1, wherein theresilient means comprises a spring loaded plunger located in saidlocking cap.

4. In an explosive-actuated tool according to claim 1, a stop pinlocated in said locking cap for preventing complete rotation of said caprelative to said body.

References Cited UNITED STATES PATENTS 2,768,375 10/ 1956 Caflin 227- 112,984,836 5/ 1961 Schenkel 227-9 3,055,008 9/ 1962 Bell et al. 227-10TRAVIS S. McGEHEE, Primary Examiner

